Pediatric Hip - HD

Introduction

Hello, I am Michael DiPietro,
MA pediatric radiologist at the University of Michigan
in Ann Arbor, and a professor of radiology
and pediatrics.
Today I'm gonna talk to you about the ultrasound
of the pediatric hip, including the painful hip
and developmental dysplasia of the hip.
I have no disclosures. And let's begin.

The Painful Hip

We're gonna talk about the painful hip
and also about developmental dysplasia of the hip.
The objectives for the painful hip are,
majority
of it involving joint effusion,
but also other causes of painful
and irritable hip objectives
regarding developmental dysplasia.
The hip are to get an overview
and concepts and orientation
and learning how to avoid some pitfalls, the child
with the painful hip.
There are several causes,
and we'll touch on some of these.
Sometimes he actually says that the hip hurts,
sometimes you only know it because the child won't move it
or will manifest with a limp.
And always remember that sometimes hip pathology,
because of referred pain, actually is experienced
as knee pain or as the problem really is in the hip.

Hip Joint Effusion

A few tips talking about hip joint effusion.
In contrast to other joints such as the,
the elbow and the ankle
and the knee, it's really difficult to detect a joint effusion when it's in the hip, and
therefore, we really rely on sonography,
plane radiographs are not reliable.
So we're gonna be talking about one issue is
how can you possibly tell if the effusion is septic
arthritis versus a more benign entity?
Transient synovitis of the hip,
sonography is certainly useful to detect the fluid,
but differentiating between those two diagnosis,
which is an important differentiate to make, we're gonna see
what can we tell based on the sonographic findings?
What can we tell perhaps based on some clinical data?
So our mission really with sonography is
to identify the effusion,
and in some cases use sonographic
guidance for aspirating it.
I'll just mention a bit about that,
but we're not gonna talk a lot about the technique of joint aspiration.
Basically, you wanna have the patient's hip in this position.
Now, sometimes because of the pain the child is gonna determine him
or herself what position the hip is gonna be in.
And one thing that's important to remember is
that if you do comparison images of the other side,
you wanna make sure that you match the position so that
you're comparing apples with apples.
But if you can, you like to have it rotated as
noted here and abducted
and extended. This is a
picture, you can tell it's an older one by the size
of the transducer from a colleague, Dr.
Harkey, but you're showing how the patient is supine
and you're following an anterior approach
to look at the hip effusion.
This anterior approach is in contradistinction
to the approach that we're gonna talk about later when we
talk about developmental dysplasia of the hip.
Here's a similar type picture, but in a small baby,
and it's showing you how you're
coming from the front, you're in a long axis relative
to the femur.
And as you can see in this diagram that you're
matching the long axis of the femoral neck
notice also, and we'll see a few more pictures
that the joint space actually extends quite a way down on the
on the femoral neck, and we really rely on that.
The upper right picture is an arthrogram with
contrast.
And you can see that the hip joint isn't just up here,
but it extends down to here.
And that's really what you see on this long axis on
the sonogram.

Appearance of Effusion

So what does it look like?
What you'll see is that the fluid in front
of the femoral neck causes the joint capsule
to distend as in this diagram with convex anteriorly.
This is the iliopsoas muscle across the top of it.
In this radiograph, which is actually this child,
there was a little bit of widening of this space,
which could suggest that there is a joint effusion,
but that is very unreliable.
These are some criteria that are used,
but mainly I think what most
of us rely on is seeing this convexity
and then seeing it more of a
convex appearance in the side
that hurts rather than on the asymptomatic side,
which would have more of this sort of appearance here.
So here's a normal, and in all of these long axis,
superiors towards your left, as you view these,
and here's the femoral neck,
and this is the joint space on the normal side.
And notice how it's bowed forward.
And it's with this anterior convexity,
because of the effusion,
the overlying iliopsoas muscle is seen here and here.
Now, a couple things I can throw you off, especially dealing
with children is cartilage being hypoechoic
can be confused sometimes with
the hypoechoic fluid.
So in this picture, we're actually quite high,
and there's the cartilaginous labrum of the hip joint, and here's cartilage
over the femoral head.
So don't confuse that. The labrum is not the effusion.
And here's a picture without the markers on it.
The cartilage of the femoral head is not the effusion.
Here's another one, and you're gonna see in a moment,
this is more prominent in children
because they have much more cartilage than this.
This is the effusion down over the femoral neck.
And here's a picture, it's a small one in this case, not
as bow as the other case was,
but that's where you look for the effusion.
And in cases where you're gonna aspirate it, that's
where you go is down here.
If you try to get into this space up here,
you're gonna hit the labrum and you're not gonna get in.
So this is really
where pay dirt is at the femoral neck.
So again, comparing the two sides, we always like
to have the two hips in the same position,
same amount of rotation.
This is a small effusion here, no effusion here.
This is a picture from colleague Dr.
Harkey, and this is a child.
So there's actually much more cartilage than we
saw in the other examples.
And there can even be more if the child is even younger
and there's less ossification of the femoral head.
And you do not wanna confuse this with an effusion.
This is just cartilage over the head.
Another finding, which you'll sometimes see is here,
and some people look at this
and think this, there's debris in the joint space,
but it isn't, this is just a
posterior reflection of the synovium.
And this was well described some years ago from
by Dr.
Robin et al.
So basically, you come from an anterior approach.
And now we wanna talk about you
have shown that there's an effusion.
Is there any way we can tell if it's septic i.e. bacterial
infection or not?

Differentiating Septic Arthritis from Transient Synovitis

Now here's two examples.
The ones the left side over here is normal.
This side is bow, and not only is it bow,
but the capsule is very thick,
and there's a lot of echogenic debris within this fluid.
And you would be a good bet that this is a septic effusion.
And indeed it was, as you can see,
there was actually pus in the joint.
They all do not look like this, though.
For instance, here's a case where the right side's here,
and this is long axis.
And now for the first time, I'm showing you short axis
that there's a really the effusion is very small
on this left side, it also looks anechoic, but
because of clinical reasons, it ended up, it was tapped
and it was a septic hip,
even though there was a small amount of fluid.
So the size of the effusion doesn't really rule out the fact that it could be a septic hip.
Also, the fact that it's anechoic doesn't rule it out,
and that there's no thickening
of the capsule does not rule it out.
So based on those sonographic findings
that we just described, that sometimes
works, but not always.
As you saw in the second example, basically the sonographic
finding nonspecific regarding whether
or not it's septic.
But the advent of power Doppler in the late 1990s,
we thought that maybe this could help us to sort it out
and certainly help our clinical colleagues
who are seeing the patient often in the emergency
department setting.
And so we had a clinical series where we followed
numerous sequential patients being evaluated
for hip joint effusion and also an animal model that we had.
And basically the conclusion that we came to in both
of them is that when you saw a big difference,
you saw a very positive response on the power Doppler in this clinical setting that it was going to be septic.
However, the sensitivity was not perfect
because we had some patients
and also some rabbits that were falsely negative.
And we think it was because it was early
in the septic process.
So you have to be careful of that.
So if it's positive, it's a good sign
that you're dealing with a septic hip in this clinical scenario.
And if it's negative, it's still could be if
it's early in the course.
Now, again, there are other causes
of a power Doppler being positive.
For instance, the patient could have another cause for a joint inflammation such as an arthritis
or rheumatoid arthritis, et cetera.
But that's a different clinical presentation.
And then here's from the clinical series.
And you can see this was just felt
to be transient synovitis on the left.
And usually what we do is we look at the normal side
and we make our settings that we start
to get a signal on power, use the same settings, go
to the other side, and we look to see if it lights up.
And this case it didn't, in this case, it did.
Here's where we set our settings on the asymptomatic normal side.
This side, which incidentally also has a very
echogenic effusion, really lit up considerably.
And this was a septic hip.
And the rabbit model, this was pretty typical.
We had, we used the knee instead of the hip,
it was easier.
But you can see that in those in whom we produced sterile effusions, we saw this, those
that had septic effusions, we saw this,
but we did have a few that did not have all this reaction.
And again, it was earlier in the course,
some hours later.
And next day when we scan 'em again,
they did look like this.
So here's the summary that power Doppler can help,
especially if it's positive.
If it isn't, you haven't entirely exclude the
possibility of a septic hip.
So sonography is not perfect.
And there's our summary looking at
other things.
And this is a paper now from the late nineties.
But and
there's been some other work looking at this,
but basically it's looking at the clinical criteria.
And you can read these here.
And basically the way it came out was that if all four
of these factors, and then another paper from University
of Michigan added C-reactive protein, if all
of these are positive and the kid with a painful hip
with an effusion, it's almost guaranteed that
that's gonna be a septic hip.
If all of these are negative
and the kid with a painful hip
with an effusion is probably gonna be transient synovitis,
the kid with the only positive
and high likely to septic hip is probably gonna go straight
to the operating room, because they don't,
you don't only need to have the hip aspirated,
but it has to be washed out and thoroughly cleaned out.
However, in the kid where a couple
of these factors are positive,
but the others aren't, then you're in
between whether you're gonna have it or not.
And that's the case where perhaps actually doing a joint aspiration can be helpful
to then decide what should be done.
So there are still some cases
where you really wanna aspirate the joint.
Just to show you how you do it, you basically want,
use your sonography, you wanna get a target over the neck,
again, not up here.
Then you come right down on that and
hopefully get into the space.

Other Causes of Hip Pain

Now, there are other things that can affect the hip and cause hip pain.
So we wanna be careful. We
really wanna be focused on what we're doing.
But you don't wanna have tunnel vision.
You wanna look around and see other things.
And here are a few examples that we're going to see
psoas abscess is well known as a cause, is,
again, a case from Dr.
Harkey. And you can see that there's no effusion,
but the overlying iliopsoas muscle looked a little abnormal
and hypoechoic.
And then, now I'm just gonna go back and forth to a CT,
and you can see that there's a lot of these big fluid,
this is all an abscess that's involving the iliopsoas.
And actually here it is going up and up at the groin,
and you could also see it on the ultrasound.
And here it is, rip over the ilium up into the pelvis,
the iliopsoas, and here it is here.
So certainly sonography can make the diagnosis.
Sometimes the advantage of CT
or MR is that you get a more panoramic global view,
but you certainly especially if your first line
of attack is ultrasound, you wanna be mindful that there could be more going on than just the joint.
So you wanna look around a little bit.
Another example we had was this child who came in with
pain and the radiographs were not remarkable.
And even on the ultrasound, there was a convexity on this side, the side that hurt,
not on this side for comparison.
So there wasn't an effusion there.
There's some debris in it,
but in looking around, the soft tissues didn't look right.
They were more echogenic.
And this is a child who actually had overlying
myositis.
And then when they really looked more
around the leg and
over around the thigh, the tissue planes were all abnormal, although its echogenicity
and increased vascularity.
Now look at this in contrast to the other side, where the planes are very nicely maintained from subcutaneous
to muscle, but on this side, it's they're very disturbed.
So this is a kid
besides having the effusion also had myositis.
This is in short axis,
and you can see the two sides in comparison,
which are muscles here and
how it's all very swollen, distorted, et cetera.
And in this movie loop, as you're going down the leg,
you can see the myositis
and quite dramatically.
And also there's some suggestion
that there might actually be some subperiosteal fluid, which when you see that,
that's an indication that you might actually also be dealing
with osteomyelitis.
Another case, this is a child that I actually
saw in the emergency department,
and we didn't know this history at the time
that you can see here about neuroblastoma had an effusion,
and we went down and we did the sonography,
and we saw a small effusion,
but the kid's pain really seemed
to be out of proportion to that.
So we looked a little higher,
and actually he was kind of pointing
that it did bother him up a little bit more towards the pelvis.
So we scanned up in that area, and lo
and behold, what do we find
as we're going up into the pelvis?
This is long axis. The hip joint is way down here.
There's this mass that we're seeing,
and then this is in short axis.
And actually, so we told 'em
that there's a mass later on, we learned,
but no one had told us that he had been treated
for neuroblastoma a few years ago.
And actually, what this ended up being was a recurrence probably from a drop metastasis that went down and settled
and started growing on the iliopsoas and the effusion
and the hip joint was probably reactive
to the iliopsoas irritation. A few other hip cases where sonography is not really the main way we look for slipped capital femoral epiphysis.
But this is a case that my colleague Dr. Sanchez did.
And they were suspicious of that diagnosis.
The clinical story was right,
but the radiographs were not very convincing.
So he performed sonography.
And here's the normal side, and it's very, very subtle.
See how the epiphysis is offset a few
millimeters from the metaphysis.
So here it lines up.
And this ended up being a very subtle, very early left slipped
capital femoral epiphysis.
The child ended up having the femoral head pinned, which is the treatment to prevent further slippage.
Another one where there was a child, and
there was pain
and there was a finding that was suspicious
that it could be a subtle fracture on the radiograph.
And again, when doing sonography, you could see on the abnormal side that there's a rent there
as compared to this side.
This is a little bit distal to where the hip joint ends down in the femoral neck.
And then there's some echogenic material here,
which is probably some hematoma.
But there was a subtle fracture.
So again, sonography in that generally the first line
of attack for fractures.
But certainly if you have it, you don't wanna miss it.
And there could be some subtle cases where it can really help you out.
And here it is in short axis with the little buckle fracture
that we're seeing right here.
So that concludes so far, this part about the painful hip.
And these are the things that we covered.

Developmental Dysplasia of the Hip

Now, to move on to developmental dysplasia of the hip,
this is what you wanna prevent.
This is a kid
and they didn't realize it now at this age is gonna be
presenting with a limp because effectively one leg is shorter than the other
because the hip's out of the joint.
And so the goal is to miss this.
And this saying, which no one really knows
where this came from, but it's been around for a while,
it's kind of apropos for this situation.
And of course, developmental dysplasia of the hip
that is missed is a major cause
of litigation in the United States.
So your main reason for not missing it is for the benefit
of the child, but there's also a secondary
that you there can be a lot
of legal issues involved with it.
When you do miss it, we're gonna discuss some practical tips and also some pitfalls.
Why and when do you do it?
Well, I'm not gonna really discuss that as much
that's been covered in the literature very well by again,
our pediatric radiology colleagues, Dr.
Harkey, who's very well known, Karen Rosendahl and
Norway has done some incredible public health time study type studies
and basically involving all the newborns of Norway
and being able to follow them over the years.
And I'd encourage you to look up their papers
and you can see more about it. In the United States,
basically everyone is not screened for DDH,
but if you have a either an abnormal physical examination
with a click or a clunk, or if you have a risk factor
and major risk factors are being breech, other problems like torticollis
or clubfoot, which suggest
that perhaps there was some element of a packing of the child in utero
or some constraint of motion
or perhaps oligohydramnios, any risk factors.
And then we'll go ahead and we'll scan 'em.
We're gonna talk about the orientation,
which is very important in static
and dynamic aspects of the study.
The term developmental dysplasia of the hip years ago used
to be called congenital dislocated hip, but that was stopped
because they're not all dislocated
and certainly not all dislocated at birth.
But it is kind of a spectrum as you can read here, of
different forms of presentation.
And within this, you have to be careful
that when you're studying a baby soon
after birth, that there's gonna be some laxity,
which is gonna correct itself, probably, which is normal.
It's called physiologic laxity.
So you don't wanna overread that.
Basically, for many years it was a bit
of people would say, what school do you follow?
The more morphology static school of Dr.
Graf here from Austria and orthopedic surgeon,
or the more dynamic study Dr.
Harkey from the United States, a pediatric radiologist
who basically adapted the physical examination
and looked at it with ultrasound.
They actually did formally come to an agreement,
as you can see back here in the 1990s.
Most of us were doing combinations
of the both all along anyhow, but those are certainly two parts of the study.
I think they're both very important.
So orientation and technique are critical.
Slide from a colleague, Dr.
Schlesinger now at Texas Children's, just showing how you might do a the coronal technique.
Now, as you'll see later, we don't scan this way
with the hand so far from the baby,
but this was done to show transducer placement.
And you can see this is long axis to the body.
And we'll see in a moment
how this is gonna give you a view that is very similar
to an AP radiograph of the hip,
and we'll kind of use that to help fix it in your mind, what we're seeing.
So we'll be sharing some tips for doing this study, also
for teaching it, and also for explaining it
to the parents.
And I think that's very important.
And I've had some parents say they
were very appreciative of understanding what we were seeing and why was the test ordered
by their doctor, et cetera.
So in this little drawing I did years ago, you can see
what you see on a radiograph,
and the blank spots here is
because much of the bone is cartilage.
So it does not show up on the radiograph,
but does on the ultrasound.
So this is our coronal view, you can see you have labrum
or you have the unossified acetabular roof,
the lab, sometimes this is entirely called the labrum.
The true labrum is the tip of it, the fibrocartilage
and also labrum cartilage of the head.
And the greater trochanter,
a hip is a ball in a socket.
And that's actually this is the key to the exam.
This is the way I explain it
to the parents and to residents.
You wanna make sure the ball is the ball in the
socket, that's the location.
Does it stay in the socket with the stress maneuvers and the physical examination?
And is the socket well-formed?
And you can see this is a more a well-formed normal, mature
socket or acetabulum.
And this is a more immature dysplastic one.
And usually the parents catch onto this pretty quickly, and it helps for them to understand what's happening.
So this is the way we really do scan them more, and
actually an overall technique in scanning and
sonography of children is I really like
to have my hand on the child
because the kid can be in moving target,
the kid can move around.
So I actually have there,
and really my hand cradles the transducer in other parts of the body too.
You don't wanna press too hard with the transducer.
Sometimes you can get carried away and it can cause some pressure on the skin
and the kid doesn't like it.
And then you are using the other hand here
to control the leg.
And you can see the way we're set up is basically the
scanning plane is gonna give you long axis relative
to the pelvis and the body.
And you can imagine that
that's actually gonna appear like an AP
radiograph of a left hip.
Here's the same picture without the labels,
just can see what we're doing.
Sometimes I can have the parent helping
stabilizing the kid, I say like a clamshell,
and that's just so the kid doesn't roll around, especially
as I'm doing the dynamic part,
because I wanna see what the femur is doing
relative to the acetabulum.
I don't want the kid rolling all over the place
and wiggling sometimes if you're having a little trouble
finding yourself and getting oriented and properly positioned right in the hip, I say,
well just go short axis to the femur
and then just follow it right in.
It'll guide you right into it.
You have to be ambidextrous.
I think it's very cumbersome if you're only gonna scan,
let's say with your right hand,
and then you have to be cross handed.
So you really should learn how to use both hands,
especially you're doing hips.
And another point here is that I'm actually I am right-handed, so this is my non-dominant hand.
And to support it a little bit more,
I'm actually resting my wrist
and my forearm on the bed,
which secures it more instead of like having my elbows up
in the air, anything like that.
And I think that's a very important technique.
It's also a technique that can be useful if you're doing any
sonographic interventional work to kind
of stabilize yourself.

Coronal View Orientation

So I mentioned that these coronal views can be akin
to a AP radiograph.
And think of it. So here's an AP
radiograph of a pelvis.
You rotate it 90 degrees as you see here,
and that really is the view that we would get with that coronal view.
And remember the main ilium, the
the footprint is gonna be up here,
and this is what you're gonna see.
And to fix it in your mind,
this is really just like an AP radiograph
of a left hip turn on its side.
And I think that's a concept, and that helps you.
And usually the residents that are learning
they catch onto this pretty quickly.
So here we are with the guide up here.
Here's what we see, the ilium, the osseous acetabular roof, the cartilaginous roof.
Here's the head, here's the metaphysis,
which is ossified bone.
So all the shadowing,
and this is the greater trochanter cartilaginous,
greater trochanter out here.
You take this picture that you're looking at right in front
of you, rotate it 90 degrees clockwise,
and it will look just like an AP X-ray of a left hip.
Now here's one where there's a, things don't kind
of set quite right the same orientation,
but notice now the head is
not down into the acetabulum as much.
It's out a little bit, and maybe the roof is a little bit,
little bit steeper.
It's not quite as vertical in this picture,
it's a bit more of a slope to it.
So it's there's some slight subluxation
that we're seeing here, and we'll see a few
dynamic ones in a moment.
Here's one that's even out more, instead
of being down here, it's out here.
And this is the cartilaginous acetabular roof.
Actually, the cartilage is a bit thickened
and echogenic, which often accompany developmental dysplasia.
The hip, this one's actually out of the joint,
it's dislocated, and you really don't have any recognizable
cartilaginous acetabular roof here.
Some of this probably is it, it's dysmorphic.
This head should be down here.
It's hard to say much about the acetabulum
because it's just hard to see it,
but it's a very abnormal hip.
When you're when it's dislocated,
you're seeing two things.
You always keep that in mind.
You're seeing the unossified femoral head,
which should be down here.
Here's the osseous acetabular roof,
and the greater trochanter.
And in a moment, we're gonna put some
extra emphasis on the greater trochanter
because it can lead you astray in some examples.
So this is a bit of an immature acetabulum here.
And especially with Graf work, you
can actually do measurements.
You can, you try to get this ilium as horizontal
as you can on the picture, use that as a baseline,
and then draw a line there along the osseous acetabular roof.
And the angle that's here usually should be greater than 60 degrees.
You can measure it.
That's the so-called Graf alpha angle.
I'm not going into all that, you can read about it,
but basically steep is when it's steep,
it's bad, it's immature.

Transverse View Orientation

Now the short axis is a little harder to picture,
and it's basically the baby's in the same position.
But now you're short axis to the body you're coming across.
And here's a kid that's actually being scanned in the Pavlik
harness, and this is from Dr.
Harkey. And again, he's showing another variation in that,
but you can see how you're short axis.
So what is that akin to,
or what is how do you figure that out?
Well, this one takes I find it takes a little bit longer to get oriented
unless you think of CT scan as axial CT
is shot in this plane going through.
So if you think of it that way, the view
that you get on sonogram,
on sonography is sort of like a CT.
And if you think that way, it'll help you.
And I'll show you. So here's a CT scan of a, actually,
of a hip that it's in a cast, you turn it on its side.
So this is the anterior posterior pubis ischium,
triradiate cartilage.
There's the head, this is the view
that you get on sonography.
So whereas the coronal view was like a AP radiograph rotated 90 degrees.
The transverse view on ultrasound is like an axial CT
rotated 90 degrees, and you can see it depicted here.
So here's the standard orientation for the CT
rotated 90 degrees here.
That's what you see on sonography.
And your footprint is out here.
And that's posterior, and that's anterior.
Now, I've showed the pubic bone in dots
because the way the hip is here, that with it being flexed,
you're not gonna see it
because it's shadowed by the metaphysis,
the ossified portion of the femur.
If you were to bring it out of the screen
and going down, then you might, you would see it.
But I'm showing it like that
because usually I have the hip flexed
for the dynamic part of the study.
So here's what it looks like.
So this picture up here, and here we are here,
and here's the head, and this is the ischium.
And then this is a lot of the, you see a lot
of cartilage in this view.
If you're interested in acetabular morphology from
that standpoint, you have,
it's the coronal view that you rely on.
This view is very good though more also for positioning.
And I really like it the best for the dynamic study,
and we'll see that in a moment.
Anterior posterior lateral orientation like this,
if you took this sonogram rotated at 90 degrees clockwise,
it would look like an axial CT
of a left hip, just like that.
Posterior anterior here.
This head should be down here a little bit more.
It's really kind of up and riding a little bit too much.
Now, to go back for a moment to the coronal view, the plane that we've been looking at,
it is so-called Graf's
the standard plane, the coronal plane.
That's really
what you wanna see to get your morphology.
But if you explore a little bit, stay coronal,
but slide more posteriorly, this is what you're gonna see.
All this cartilage that's way, way posteriorly.
And that's all the cartilage
that we are seeing on the transverse view.
Here's the ilium. Here's all this cartilage.
You should not see femoral head in this neighborhood if
you do, it's very much displaced posteriorly.
And here's that same cartilage on the short axis transverse view of the hip and see it's very posterior.
So here it is on this view,
the posterior to the femoral head.
Here it is on this view.
And the femoral head is not in the plane.
It's coming towards us.
It's not in the picture,
but that's a important thing to be aware of.
Another picture of it here with the cartilage.
And here's the head. Now in this baby, actually,
if you look down here, these hips are both dislocated.
I mean, here's the acetabulum, and here's the head and
what you what we do oftentimes in pediatric radiology,
we just imagine looking at the morphology
of the ossified bone, we draw in where the head should be,
and it would be here.
And certainly it should be down here.
This is what it looks like on sonography. This is ilium.
You don't see anything of the acetabulum
because you can't get near it.
'cause where the hip is. And here's the femoral head.
So this is completely dislocated,
laterally and superiorly.
When I see this, what I try to do on the exam is I try
to see to what extent I can reduce the hip.
Is it reduceable or not?
Here's another one on the coronal view,
and this is what I was saying, this is that posterior
acetabular cartilage,
and you have the femoral head right over it.
And that they shouldn't be anywhere near each other in
this in the coronal views.
And then in the transverse view, again,
the head is way out here, laterally
and posteriorly, this head should be way down here.
And here's the ossified metaphysis there.
So on this this is a transverse view.
This is normal. It's just it is playing over
and over again like a loop.
And you can see anterior posterior, this is lateral, the
where coming in gluteal muscles coming
around every once in while I see this little
hypoechoic hook, which is the greater trochanter.
Lemme get it going again.
Here's the ischium here
and the cartilage over it.
And this looks like it's normal now.
Now what we're doing is we are before I was just going in
and out, now I'm actually abducting and adducting.
And you can see by the way, the this ossified portion is moving.
So when I abduct, I'm moving the hip away from the midline.
There it is ab. Now add with a d, add
with a B, add with a D.
Now, this is important because this is an important part
of the dynamic examination.
'cause hips that are really loose when you adduct them,
and again, I'll show you when it's in adduction,
it's a deducted.
Now when now it's abducted.
When they're adducted, they tend to slip.
And sometimes the slip is very subtle.
It's just widening of this space here
between the head and the ischium.
And then with abduction, the hips tend to come back in.
So abduction, bringing the knee away from the midline,
bringing the femur away from the midline tends
to reduce the hip.
Adduction with the knee towards the midline tends to
cause it to sublux.
This is normal. It's going through abduction and adduction.
And this distance here in the six o'clock position
is staying the same.
The head's not slipping.
You can see how all this normal, very posterior cartilage
of the acetabulum is coming in
and out of the picture, you can see the hook up here
of the greater trochanter coming in
and outta the picture, the gluteal muscles coming
around to and over it.

Dynamic Examination and Laxity

Testing for laxity,
the clinicians will do the Barlow maneuver.
You push down like a piston.
Now in the physical examination,
you just feel the one hip going down farther.
The leg is going closer towards the bed.
We actually watch it on sonography.
This is a coronal view.
Superiors to your left, this is normal.
You can see as I'm scanning the greater trochanter is coming into the picture.
Here's the head, a little bit more of the metaphysis,
a little bit more posterior scanning there,
and you see more cartilage.
But this is all a normal.
This one is there's some laxity on this coronal view.
See right here, this distance is a little wider.
See how it's kind of slipping out a little bit.
Generally, if you drop a line down from the horizontal,
if you had the ilium horizontal, you drop a line down,
about 50% of the head should be medial to that line.
So we talk about 50% osseous coverage of the femoral head.
This is clearly less than that.
Now the thing is that yes, there is actually,
there's some subluxation, but the child
is only a day of age.
So this could just be normal physiologic laxity from all
of the mom's hormones, which allowed her pelvis to expand so she could deliver the baby.
The baby has some of these in him or her,
and that's probably what we're seeing here.
And after a few weeks, it should firm up.
There's another coronal view here.
Now now we're out about a month.
And this is one where the hip is out.
It's perched out here a bit. It should be down here.
Here's the acetabulum.
And actually, what I'm trying to do isn't to see if it pushes out, it's baseline was out.
I'm trying to see how well I can reduce it by abducting,
and it's not reducing very well here.
We've gone to a transverse view.
Now, this is the view, if you take this,
rotate it 90 degrees clockwise,
it would look like an axial CT of a left hip
anterior posterior.
And I'm just abducting
and adducting, ab, ab, ab, ab.
And you can see it's not slipping.
There's no widening of this space here.
This is all normal in this one week old.
This one is a month old.
It's that I think the other one we saw.
Now it's on transverse view.
And notice how it's tending
to slip out this way.
I can't really get it fully reduced on the ischium.
And this is a lax hip.
Now, another view that I use as an anterior approach, it gives me a little extra information.
It's ancillary. I do not do it instead of the other views.
But sometimes I feel it helps me a bit.
And here what I'm doing is just scanning from the front.
I tend to use like a
more tightly curved one is just easier.
And you can see how I'm scanning.
And there's some investigators in Japan
and also in I think Sweden
that have done some of this.
And sometimes it just gives me a another feel for
the dynamic study of what's happening.
And actually, you can see this very, very directly with the Barlow maneuvers,
the pictures aren't as pretty.
Now if you look here, this is exactly like this view
and the bladder would be over here.
And but you can kind of make out, if you can see here
how there's this thunk that's going down
and this is the hip being displaced and dislocated.
So this is a good example of that,
and that's what we're seeing.
So it's not a substitute.
I use it for illustrative education confirmation.
I always do it at the end of the study.
'cause babies sometimes cry with it.
And there's nothing I'm doing any
differently to in this.
I don't think I'm hurting them.
I figure maybe they have more cutaneous nerve endings
in that part of their body.
So they just sense it more than they do if you're just
laterally over their thigh.
And you gotta be careful, it's a great view.
You can get peed on very easily, so you have
to make sure you keep 'em covered.
The parents usually get a good laugh when I check
the bladder first and they know why I'm doing it, so that livens things up a little bit.

Pitfalls in DDH Ultrasound

So in the words of Dr.
Harkey, here again, has been one
of the foremost investigators.
This is some advice he gives about doing it, about doing DDH. A couple of pitfalls.
One real classic one is that it's hard.
You have to get the transducer exactly the right position.
It's very easy. It's almost like an airplane.
You have roll pitch and yaw and plus translation.
So it's really easy to not be in the right plane.
And you wanna get as best you can, the ilium
to be horizontal the acetabulum.
And you can see, and I'm intentionally going off
to show you, but when we get it,
you want the osseous acetabular roof to be
as deep as you can get it.
And you wanna be able to see the little echogenic fibrocartilage at the tip of the labrum.
So there for that moment, that was the right plane.
But you can see in getting to it, you
have a view here.
It looks like you have a very shallow acetabulum.
And in the early days of doing this, some
of our sonographers until they got used to it,
were giving us views like this.
And then of course we go in
and then you can correct it.
One thing I find useful so that you don't fall into
that trap, is the first view I'll get is this.
I'll just have the kid flat on the back,
the legs extended like this,
and they just come straight in from the side.
And it's a very easy view to get.
And this was taught to us by a visiting faculty we had for a few years from Switzerland, I'll mention in a moment.
And this is the way they did their screening exams.
And my feeling is if you do this
and you get a hip that looks pretty normal.
I mean, I won't end here, but if it looks pretty normal
and then you go on and turn the kid up
and you're getting screwball results
and the acetabulum doesn't look normal,
it's probably your technique.
So the Boris Eckart is the guy
that told us about it.
So we locally, we just call it the Eckart
view, and there's Dr.
Eckart here with other colleagues from Switzerland
who have also spent various time with us.
There's this our section leader, Dr.
Strouse, and that's me at one of the European meetings.
Another problem you can have is that if the kid has an underlying problem, as you see here,
like a contracture, arthrogryposis, these things they can really throw you off if you don't realize it.
And again, it can be a cause of problems.
So this one is kind of classic
and we've had a few instances of it.
And some years ago, I'm gonna orient it again
to the where the greater trochanter is here.
And this is a picture. This is one you, it's
the plane that you wanna be in.
There's a greater trochanter.
And now I'm intentionally scanning a little bit more
posteriorly, a little bit more posteriorly.
You really can't see the head now,
but if you didn't know where you were, what you were doing,
you could mistake that perhaps
as the femoral head.
And sometimes that happens,
especially when you can't get the right orientation
because as an underlying anomaly, such as a hip contracture.
So this came to mind some years ago,
but other places have reported this also.
This kid had a fracture there
and there was a concern of where is the hip
and where's the femoral head?
Now actually, you're gonna see this's gonna be right here,
but it wasn't clear this sonogram was done.
It's an old one, but the person reading it
couldn't see the acetabulum saw this, had not seen the radiograph,
and was not aware of the kid's underlying condition,
and then jumped to the conclusion, this
is a small dysmorphic displaced femoral head, and the hip is out.
They did an arthrogram and the hip was in,
and the orthopedic surgeon wasn't too happy.
But that really brought to mind that
with the person, that what they were really seeing was the
greater trochanter.
And this is analogous to this,
and this was the case, and this has happened.
The last thing, a complication of treatment, babies
with DDH can get ischemic necrosis,
but it's a complication of treatment, not
of the underlying entity.
So here's a kid, and you can see at this time the hip,
and there's kind of a shallow ish acetabulum.
It's not fully reduced. Here it is on short axis view.
This head should be down here more.
The kid is placed in a harness
and actually did not have any problems.
But I was able to demonstrate what happens here.
The hip on this transverse view
is adducted.
The knee is coming towards the midline.
Here's the head, and you're seeing Doppler signal
within the femoral head.
Then I abducted and the signal is gone.
Here it is on the movie.
So I don't always see this,
but it was just I was doing this
as a teaching example.
Adduction, there's flow
to the head abduction, there isn't.
And that's a known problem.
Therefore, when these kids are fitted for the harness,
the orthopedic surgeons, there's a critical zone.
They wanna be sure that they do not overly abduct the hip.
And there's a temptation to do that.
You know, they're saying, I'm gonna get these babies in, I'm gonna really reduce this.
Well, you can overdo it and have too much of a good thing.
And then you fall into this problem.
And here it is on the coronal view.
This is with adduction, which is actually the
position with the knee towards the midline
where the hip tends to sublux more and abduction.
See, you've reduced it, but at the cost
of losing the circulation.
So you have to be aware of that.
And this is pretty well established in the pediatric
orthopedic literature.
So they're aware of it. And but you know, we should also,
and this just happens to be a
this is an unusually good example of it, so
that's why I'm showing it to you.

Summary of DDH

So in summary about DDH,
the key concepts are basically it's a ball in a socket.
And and
then if you understand how the
coronal view is basically like an AP radiograph turn on
its side, and the transverse short axis view is basically
like a CT scan turn on its side.
I think it'll help you out.
You have to learn to be ambidextrous,
keep your hands on the kid
and cradle a transducer, which is good advice for all
of pediatric sonography.
And in that in this view here, that with the patient's supine
and coming in as a start is a good way
to at least get a ballpark figure.
And if the hip looks pretty normal, then
you should be getting pretty normal
results when you turn the kid up.
And if you don't, it's probably your technique.
And with that, we'll end this
and thank you very much for your attention.